Characterization of mammalian orthoreoviruses isolated from faeces of pigs in Zambia.

Hayato Harima,Bernard M Hang’Ombe,Aaron S Mweene,Yasuko Orba,Gabriel Gonzalez,Ayato Takada,Mao Isono,Edgar Simulundu,Kosuke Okuya,Hirofumi Sawa,Masahiro Kajihara,Eugene C Bwalya,Michihito Sasaki,Yongjin Qiu

doi:10.1099/jgv.0.001476

Hayato Harima, Bernard M Hang’Ombe + Show 12 more

Open Access

https://doi.org/10.1099/jgv.0.001476

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Abstract

Mammalian orthoreovirus (MRV) has been identified in humans, livestock and wild animals; this wide host range allows individual MRV to transmit into multiple species. Although several interspecies transmission and genetic reassortment events of MRVs among humans, livestock and wildlife have been reported, the genetic diversity and geographic distribution of MRVs in Africa are poorly understood. In this study, we report the first isolation and characterization of MRVs circulating in a pig population in Zambia. In our screening, MRV genomes were detected in 19.7 % (29/147) of faecal samples collected from pigs by reverse transcription PCR. Three infectious MRV strains (MRV-85, MRV-96 and MRV-117) were successfully isolated, and their complete genomes were sequenced. Recombination analyses based on the complete genome sequences of the isolated MRVs demonstrated that MRV-96 shared the S3 segment with a different MRV isolated from bats, and that the L1 and M3 segments of MRV-117 originated from bat and human MRVs, respectively. Our results suggest that the isolated MRVs emerged through genetic reassortment events with interspecies transmission. Given the lack of information regarding MRVs in Africa, further surveillance of MRVs circulating among humans, domestic animals and wildlife is required to assess potential risk for humans and animals.

Highlights

Orthoreoviruses, belonging to the genus Orthoreovirus in the family Reoviridae, are non-enveloped, icosahedral, segmented double-stranded RNA viruses that infect vertebrates and invertebrates [1].The orthoreovirus genome consists of 10 dsRNA segments divided into three size classes based on the characteristic mobility by gel electrophoresis, including three large segments (L1–L3), three medium segments (M1–M3), and four small segments (S1–S4) [1]
We report the isolation and characterization of Mammalian orthoreovirus (MRV) circulating in a pig population in Zambia
19.7% of pigs in Zambia were positive for MRVs, which were detected in all investigated areas, including Lusaka, Chilanga, Chibombo, and Kafue

Summary

Introduction

The orthoreovirus genome consists of 10 dsRNA segments divided into three size classes based on the characteristic mobility by gel electrophoresis, including three large segments (L1–L3), three medium segments (M1–M3), and four small segments (S1–S4) [1]. The genome is encased in two concentric capsid protein shells [1]. This structural feature contributes to the thermostability and protease resistance of its virion and play a role in the entry process of orthoreoviruses [2,3,4,5,6,7,8]. The serotype specificity is determined by σ1 protein encoded in the S1 segment, which has the largest sequence divergence [12,13,14]

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